Plz explain it in a clear manner

Dear Student
Mass of the body remains same everywhere.
Weight of the body changes as acceleration due to gravity of the place changes.
So 
If man weighs 600 N on Earth then
W = mg
m = W/g = 600 /10 = 60 Kg., mass of man on Earth.


Now on moon also mass remains same. so m = 60 kg on moon too.

Now on moon W = 100 N
So 
100 = 60 g_m
g_m  =100/60 = 10/6  m/s² 
So  acceleration due to gravity on moon is 10 /6 m/s²

Regards